chore(release): bump version to 1.0.0

Fills in the CHANGELOG.md entry for the checkpoint-anchoring security fix,
fuzzing infrastructure and its findings, OP_RETURN/coinbase-tag decoding,
and localization fixes since 0.9.1 (see previous commits), and bumps
<Version>/versionCode across the App and Android head csproj files ahead
of the tag.

CHANGELOG.md

@@ -5,6 +5,108 @@ Technical changelog for PalladiumWallet. Format loosely follows
 by subsystem rather than strictly by date, since `0.9.0` is the first
 release and covers the full history from the initial commit.
 
+## [1.0.0] — 2026-07-09
+
+First stable release. Closes the last open security gap from 0.9.x (header
+trust was not actually anchored to any checkpoint), fixes several crash
+paths found by a new fuzzing harness, and adds OP_RETURN/coinbase-tag
+decoding to the transaction detail view.
+
+### Security
+
+- `WalletSynchronizer.AnchorToCheckpointAsync`: header trust is now actually
+  anchored to `ChainProfiles.Mainnet.Checkpoints` (24 real `[height, hash,
+  bits]` checkpoints pulled from a fully-synced node, every 20,000 blocks
+  plus one near tip). Previously the checkpoint array was empty and the
+  methods meant to enforce it (`MatchesCheckpoint`/`IsValidChild`) were
+  never called — on this LWMA chain, where PoW can't be recomputed
+  client-side, a malicious or eclipsing server could hand back any
+  internally-consistent header for a Merkle proof with nothing tying it to
+  the real chain. For every header used in a Merkle proof, the intervening
+  headers are now downloaded back to the nearest checkpoint and verified as
+  an unbroken prev-hash chain terminating in that checkpoint's exact hash
+  (memoized per sync session). Testnet/Regtest remain unanchored (no node
+  available to source checkpoints from); a missing checkpoint is a no-op,
+  not a failure.
+- New fuzzing harness (`tests/PalladiumWallet.Fuzz`, SharpFuzz-based): one
+  target per untrusted-input parser (header, Merkle proof, peer list,
+  wallet file, mnemonic/key/address/amount), each encoding that parser's
+  documented error contract. Found and fixed:
+  - `Bip39.TryParse` threw `NotSupportedException` on text resembling no
+    wordlist instead of failing gracefully.
+  - `ElectrumApi.ParsePeers` threw on any `server.peers.subscribe` response
+    shape other than the expected `[ip, hostname, [features...]]`, and on a
+    JSON string containing invalid UTF-8.
+  - `EncryptedFile.Decrypt` let a tampered/corrupted wallet file escape as
+    raw `JsonException`/`FormatException`/`ArgumentNullException` instead of
+    the documented `WrongPasswordException`/`InvalidDataException`
+    contract; worse, the PBKDF2 iteration count was read from the
+    (attacker-controlled) container with no upper bound — a tampered file
+    demanding e.g. 2³¹ iterations would hang the wallet on open. Iteration
+    count is now clamped to 10,000,000.
+  - `CertificatePinStore.Load`: a corrupted pin file blocked every SSL
+    connection until manually deleted; now falls back to first-contact
+    TOFU like `ServerRegistry` already did.
+  - The seed corpus (incl. a regression input per fixed finding) replays
+    inside `dotnet test` via `FuzzCorpusTests`, so a fix can't silently
+    regress.
+- `SECURITY.md` corrected: PBKDF2 parameters (600,000 iterations / 16-byte
+  salt, not the pre-hardening 100,000 / 32-byte), a stale file reference,
+  and disclosure of the AI-assisted testing methodology used (adversarial
+  fake-server simulation, property-based fuzzing, targeted security
+  review) as a complement to, not a replacement for, independent review.
+
+### Added
+
+- Transaction detail view now decodes OP_RETURN output payloads (UTF-8, or
+  hex if the bytes aren't valid text — multiple OP_RETURN outputs in one tx
+  are each decoded independently) and coinbase scriptSig pool tags (e.g.
+  `/slush/`, extracted as printable-ASCII runs amid the binary BIP34
+  height/extranonce). Both were previously dropped entirely — discarded
+  once no destination address could be derived from the script.
+- Help overlay: "User guide" button next to "Report a bug", linking to
+  `USERGUIDE.md` on GitHub.
+- `USERGUIDE.md`: full end-user reference for GUI and CLI (wizard flows,
+  script types, fees, gap limit, TOFU cert pinning, CLI commands) with the
+  exact numbers the software enforces.
+
+### Fixed
+
+- Send/Donate/Sync/Wizard view models wrote status/error strings directly
+  in Italian regardless of the active language; routed through `Loc` with
+  the missing keys added. `CertificatePinMismatchException` no longer
+  bakes an Italian message into `.Message` — it exposes `Host`/`Port` for
+  the UI to translate.
+- CLI (`src/Cli/Program.cs`) printed all output in Italian regardless of
+  the code/docs-are-English-only policy; translated every user-facing
+  string and comment.
+
+### Testing
+
+- Test suite expanded from 307 to 392 tests, closing coverage gaps in:
+  checkpoint-anchoring (including the memoization and non-generic-retry
+  branches), the PoW-checked branch of `BlockHeaderInfo.IsValidChild`
+  (never run since every profile sets `SkipPowValidation`), all 8 BIP-39
+  wordlist languages plus the empty-input guard, SLIP-132 rejection of
+  malformed/corrupted keys, `TransactionFactory`'s standardness-policy
+  rejection, `ImportedKeyAccount`'s fund-safety fallbacks,
+  `WalletLoader`'s defensive branches for corrupted files,
+  `PalladiumNetworks.For`/`INetworkSet`, `AppPaths`' full data-root
+  precedence chain (via new internal override seams), `UpdateChecker`
+  end-to-end via a stub-transport seam, and `ElectrumClient`'s
+  multi-segment response dispatch.
+- OP_RETURN/coinbase-tag decoding covered: UTF-8 text, binary fallback to
+  hex, multiple OP_RETURN outputs in one tx, pool-tag extraction, and the
+  absence of false positives on standard outputs/inputs.
+
+### Documentation
+
+- `AGENTS.md`/`CLAUDE.md` re-synced (had drifted) and reformatted from
+  dense prose to scannable bullet lists; a stale `SECURITY.md` file
+  reference fixed.
+- `README.md` test-coverage section and `SECURITY.md` updated to describe
+  the checkpoint anchoring and fuzzing guarantees actually enforced now.
+
 ## [0.9.1] — 2026-07-02
 
 ### Testing

src/App.Android/PalladiumWallet.App.Android.csproj

@@ -8,8 +8,8 @@
     <Nullable>enable</Nullable>
     <ApplicationId>io.github.davide3011.palladiumwallet</ApplicationId>
     <!-- ApplicationVersion = versionCode (intero), ApplicationDisplayVersion = versionName -->
-    <ApplicationVersion>2</ApplicationVersion>
+    <ApplicationVersion>3</ApplicationVersion>
-    <ApplicationDisplayVersion>0.9.1</ApplicationDisplayVersion>
+    <ApplicationDisplayVersion>1.0.0</ApplicationDisplayVersion>
     <AndroidPackageFormat>apk</AndroidPackageFormat>
     <!-- Includi le assembly .NET DENTRO l'apk: senza, in Debug si usa il Fast
          Deployment (assembly spinte via adb da `dotnet run`) e un apk installato

src/App/PalladiumWallet.App.csproj

@@ -6,7 +6,7 @@
     <TargetFramework>net10.0</TargetFramework>
     <!-- Versione dell'applicazione: unico punto da modificare. Compare nel
          titolo della finestra ed è incisa nei binari pubblicati. -->
-    <Version>0.9.1</Version>
+    <Version>1.0.0</Version>
     <Nullable>enable</Nullable>
     <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
   </PropertyGroup>

src/App/ViewModels/TransactionDetailsViewModel.cs

@@ -64,13 +64,17 @@ public sealed class TransactionDetailsViewModel
         RbfText = loc[d.RbfSignaled ? "tx.yes" : "tx.no"];
         Inputs = new ObservableCollection<TxIoRow>(d.Inputs.Select((i, n) => new TxIoRow(
             i.IsCoinbase ? loc["tx.coinbase"] : $"{i.PrevTxid}:{i.PrevIndex}",
-            i.IsCoinbase ? loc["tx.coinbase.newcoins"] : i.Address ?? "—",
+            i.IsCoinbase
+                ? i.CoinbaseTag is { Length: > 0 } tag
+                    ? $"{loc["tx.coinbase.newcoins"]} — {tag}"
+                    : loc["tx.coinbase.newcoins"]
+                : i.Address ?? "—",
             i.AmountSats is { } a ? CoinAmount.FormatIn(a, unit) : "—",
             i.IsMine)));
 
         Outputs = new ObservableCollection<TxIoRow>(d.Outputs.Select(o => new TxIoRow(
             $"#{o.Index}",
-            o.Address ?? $"({o.ScriptType})",
+            o.Address ?? (o.OpReturnText is { Length: > 0 } msg ? $"OP_RETURN: {msg}" : $"({o.ScriptType})"),
             CoinAmount.FormatIn(o.AmountSats, unit),
             o.IsMine)));
     }

src/Core/Wallet/TransactionInspector.cs

@@ -5,12 +5,18 @@ using PalladiumWallet.Core.Spv;
 namespace PalladiumWallet.Core.Wallet;
 
 /// <summary>An input of a transaction, with the spent output resolved from the server.</summary>
+/// <param name="CoinbaseTag">
+/// Printable ASCII runs (e.g. pool tags like "/slush/") extracted from the coinbase
+/// scriptSig; null for non-coinbase inputs or if no printable text was found.
+/// </param>
 public sealed record TxInputInfo(
-    string PrevTxid, uint PrevIndex, long? AmountSats, string? Address, bool IsMine, bool IsCoinbase);
+    string PrevTxid, uint PrevIndex, long? AmountSats, string? Address, bool IsMine, bool IsCoinbase,
+    string? CoinbaseTag = null);
 
 /// <summary>An output of a transaction.</summary>
+/// <param name="OpReturnText">Decoded OP_RETURN payload (UTF-8, or hex if not valid text); null otherwise.</param>
 public sealed record TxOutputInfo(
-    uint Index, long AmountSats, string? Address, string ScriptType, bool IsMine);
+    uint Index, long AmountSats, string? Address, string ScriptType, string? OpReturnText, bool IsMine);
 
 /// <summary>
 /// Complete transaction data assembled by querying the server: the raw transaction
@@ -105,8 +111,9 @@ public static class TransactionInspector
         {
             var o = tx.Outputs[i];
             var addr = AddrOf(o.ScriptPubKey);
+            var opReturn = addr is null ? OpReturnTextOf(o.ScriptPubKey) : null;
             outputs.Add(new TxOutputInfo(
-                (uint)i, o.Value.Satoshi, addr, ScriptType(o.ScriptPubKey),
+                (uint)i, o.Value.Satoshi, addr, ScriptType(o.ScriptPubKey), opReturn,
                 addr is not null && ownedAddresses.Contains(addr)));
         }
 
@@ -134,7 +141,7 @@ public static class TransactionInspector
         {
             if (tx.IsCoinBase)
             {
-                inputs.Add(new TxInputInfo("", inp.PrevOut.N, null, null, false, true));
+                inputs.Add(new TxInputInfo("", inp.PrevOut.N, null, null, false, true, CoinbaseTagOf(inp.ScriptSig.ToBytes())));
                 continue;
             }
 
@@ -189,4 +196,48 @@ public static class TransactionInspector
         }
         catch { return "—"; }
     }
+
+    /// <summary>Decodes an OP_RETURN output's pushed data as UTF-8 text, falling back to hex if it isn't valid text.</summary>
+    private static string? OpReturnTextOf(Script script)
+    {
+        if (!script.IsUnspendable) return null;
+        try
+        {
+            var data = script.ToOps().Skip(1)
+                .Where(op => op.PushData is { Length: > 0 })
+                .SelectMany(op => op.PushData)
+                .ToArray();
+            return data.Length == 0 ? null : DecodeUtf8OrHex(data);
+        }
+        catch { return null; }
+    }
+
+    private static string DecodeUtf8OrHex(byte[] data)
+    {
+        var text = System.Text.Encoding.UTF8.GetString(data);
+        var looksLikeText = !text.Contains('�') && text.All(c => !char.IsControl(c) || c is '\n' or '\r' or '\t');
+        return looksLikeText ? text : "0x" + Convert.ToHexString(data);
+    }
+
+    /// <summary>
+    /// Extracts printable-ASCII runs (≥4 chars) from a coinbase scriptSig, e.g. pool
+    /// tags like "/slush/" embedded among the binary BIP34 height and extranonce.
+    /// </summary>
+    private static string? CoinbaseTagOf(byte[] scriptSig)
+    {
+        var runs = new List<string>();
+        var run = new System.Text.StringBuilder();
+        void Flush()
+        {
+            if (run.Length >= 4) runs.Add(run.ToString());
+            run.Clear();
+        }
+        foreach (var b in scriptSig)
+        {
+            if (b is >= 0x20 and <= 0x7E) run.Append((char)b);
+            else Flush();
+        }
+        Flush();
+        return runs.Count == 0 ? null : string.Join(" ", runs);
+    }
 }

tests/PalladiumWallet.Tests/Wallet/TransactionInspectorTests.cs

@@ -195,6 +195,139 @@ public class TransactionInspectorTests
         Assert.Equal(0, server.CallCount("blockchain.block.header"));
     }
 
+    [Fact]
+    public async Task Un_output_OP_RETURN_con_testo_UTF8_viene_decodificato()
+    {
+        var account = Account();
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("hello palladium"u8.ToArray()));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        var opReturn = Assert.Single(details.Outputs, o => o.Index == 1);
+        Assert.Null(opReturn.Address);
+        Assert.Equal("hello palladium", opReturn.OpReturnText);
+    }
+
+    [Fact]
+    public async Task Un_output_OP_RETURN_con_dati_binari_ricade_su_hex()
+    {
+        var account = Account();
+        byte[] data = [0x00, 0x01, 0xFF, 0xFE, 0x02];
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey(data));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        var opReturn = Assert.Single(details.Outputs, o => o.Index == 1);
+        Assert.Equal("0x" + Convert.ToHexString(data), opReturn.OpReturnText);
+    }
+
+    [Fact]
+    public async Task Piu_output_OP_RETURN_nella_stessa_tx_sono_decodificati_singolarmente()
+    {
+        var account = Account();
+        var tx = Net.CreateTransaction();
+        tx.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
+        tx.Outputs.Add(Money.Satoshis(1_000_000), account.GetReceiveAddress(0));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("first"u8.ToArray()));
+        tx.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey("second"u8.ToArray()));
+
+        var (server, client) = await StartAsync(tx);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, tx.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: 1_000_000, verified: true);
+
+        Assert.Equal("first", details.Outputs.Single(o => o.Index == 1).OpReturnText);
+        Assert.Equal("second", details.Outputs.Single(o => o.Index == 2).OpReturnText);
+    }
+
+    [Fact]
+    public async Task Un_output_normale_non_ha_testo_OP_RETURN()
+    {
+        var (funding, spend, _, account) = SpendPair();
+        var (server, client) = await StartAsync(funding, spend);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, spend.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: -610_000, verified: true);
+
+        Assert.All(details.Outputs, o => Assert.Null(o.OpReturnText));
+    }
+
+    [Fact]
+    public async Task Il_tag_pool_nello_scriptSig_della_coinbase_viene_estratto()
+    {
+        var account = Account();
+        var coinbase = Net.CreateTransaction();
+        // BIP34 height push (binary) followed by a pool tag (printable ASCII).
+        var scriptSig = new Script(Op.GetPushOp(190), Op.GetPushOp("/slush/"u8.ToArray()));
+        coinbase.Inputs.Add(new TxIn(new OutPoint(uint256.Zero, 0xffffffff), scriptSig));
+        coinbase.Outputs.Add(Money.Satoshis(5_000_000_000), account.GetReceiveAddress(0));
+
+        var (server, client) = await StartAsync(coinbase);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, coinbase.GetHash().ToString(), tipHeight: 200, height: 190,
+            Owned(account), netSats: 5_000_000_000, verified: true);
+
+        var input = Assert.Single(details.Inputs);
+        Assert.True(input.IsCoinbase);
+        Assert.Contains("/slush/", input.CoinbaseTag);
+    }
+
+    [Fact]
+    public async Task Uno_scriptSig_coinbase_senza_testo_stampabile_non_produce_tag()
+    {
+        var account = Account();
+        var coinbase = Net.CreateTransaction();
+        var scriptSig = new Script(Op.GetPushOp([0x00, 0x01, 0x02]));
+        coinbase.Inputs.Add(new TxIn(new OutPoint(uint256.Zero, 0xffffffff), scriptSig));
+        coinbase.Outputs.Add(Money.Satoshis(5_000_000_000), account.GetReceiveAddress(0));
+
+        var (server, client) = await StartAsync(coinbase);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, coinbase.GetHash().ToString(), tipHeight: 200, height: 190,
+            Owned(account), netSats: 5_000_000_000, verified: true);
+
+        var input = Assert.Single(details.Inputs);
+        Assert.Null(input.CoinbaseTag);
+    }
+
+    [Fact]
+    public async Task Un_input_normale_non_ha_tag_coinbase()
+    {
+        var (funding, spend, _, account) = SpendPair();
+        var (server, client) = await StartAsync(funding, spend);
+        await using var _ = server; await using var __ = client;
+
+        var details = await TransactionInspector.FetchAsync(
+            client, Net, spend.GetHash().ToString(), tipHeight: 200, height: 101,
+            Owned(account), netSats: -610_000, verified: true);
+
+        Assert.All(details.Inputs, i => Assert.Null(i.CoinbaseTag));
+    }
+
     [Fact]
     public async Task La_cache_delle_tx_evita_le_richieste_al_server()
     {